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Wirestam R, Larsen VA, Stubgaard M, Thomsen C, Vikhoff B, Larsson HBW, Ståhlberg F, Henriksen O. Deuterium MR Spectroscopy at 4.7 T. Acta Radiol 2016. [DOI: 10.1177/028418519503600116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Deuterium MR spectroscopy was used for the determination of tissue blood flow (TBF). The tracer D2O was injected into the tissue of interest, and tracer washout was followed using a 4.7 T spectroscopy/imaging unit. Normal subcutaneous tissue in rats was studied, as well as tissue influenced by vasoactive agents (papaverine and adrenaline). The vasoactive agents introduced changes of 40% in TBF, compared with normal tissue. Normal tissue measurements were repeated using various D2O injection volumes (5–400 μl). The injection volume 5 μl gave TBF 11.7 ± 2.0 ml/100 g·min (mean ± 1 SD). This value was 40% higher than corresponding values observed at larger injection volumes (200–400 μl). This injection volume effect is probably partly due to a capillary dilution caused by tracer administration, and partly related to the non-physiological deuterium signal decrease observed in dead rats. Blood flow measurements in human colon tumours implanted in nude mice showed a rather poor reproducibility, not improved by the use of a multiple site injection technique.
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Cuenod C, Balvay D. Perfusion and vascular permeability: Basic concepts and measurement in DCE-CT and DCE-MRI. Diagn Interv Imaging 2013; 94:1187-204. [DOI: 10.1016/j.diii.2013.10.010] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Detre JA, Rao H, Wang DJJ, Chen YF, Wang Z. Applications of arterial spin labeled MRI in the brain. J Magn Reson Imaging 2012; 35:1026-37. [PMID: 22246782 DOI: 10.1002/jmri.23581] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 12/15/2011] [Indexed: 01/18/2023] Open
Abstract
Perfusion provides oxygen and nutrients to tissues and is closely tied to tissue function while disorders of perfusion are major sources of medical morbidity and mortality. It has been almost two decades since the use of arterial spin labeling (ASL) for noninvasive perfusion imaging was first reported. While initial ASL magnetic resonance imaging (MRI) studies focused primarily on technological development and validation, a number of robust ASL implementations have emerged, and ASL MRI is now also available commercially on several platforms. As a result, basic science and clinical applications of ASL MRI have begun to proliferate. Although ASL MRI can be carried out in any organ, most studies to date have focused on the brain. This review covers selected research and clinical applications of ASL MRI in the brain to illustrate its potential in both neuroscience research and clinical care.
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Affiliation(s)
- John A Detre
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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4
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Koretsky AP. Early development of arterial spin labeling to measure regional brain blood flow by MRI. Neuroimage 2012; 62:602-7. [PMID: 22245338 DOI: 10.1016/j.neuroimage.2012.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/16/2011] [Accepted: 01/01/2012] [Indexed: 12/31/2022] Open
Abstract
Two major avenues of work converged in the late 1980's and early 1990's to give rise to brain perfusion MRI. The development of anatomical brain MRI quickly had as a major goal the generation of angiograms using tricks to label flowing blood in macroscopic vessels. These ideas were aimed at getting information about microcirculatory flow as well. Over the same time course the development of in vivo magnetic resonance spectroscopy had as its primary goal the assessment of tissue function and in particular, tissue energetics. For this the measurement of the delivery of water to tissue was critical for assessing tissue oxygenation and viability. The measurement of the washin/washout of "freely" diffusible tracers by spectroscopic based techniques pointed the way for quantitative approaches to measure regional blood flow by MRI. These two avenues came together in the development of arterial spin labeling (ASL) MRI techniques to measure regional cerebral blood flow. The early use of ASL to measure brain activation to help verify BOLD fMRI led to a rapid development of ASL based perfusion MRI. Today development and applications of regional brain blood flow measurements with ASL continues to be a major area of activity.
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Affiliation(s)
- Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Silva AC, Liu JV, Hirano Y, Leoni RF, Merkle H, Mackel JB, Zhang XF, Nascimento GC, Stefanovic B. Longitudinal functional magnetic resonance imaging in animal models. Methods Mol Biol 2011; 711:281-302. [PMID: 21279608 PMCID: PMC4748954 DOI: 10.1007/978-1-61737-992-5_14] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Functional magnetic resonance imaging (fMRI) has had an essential role in furthering our understanding of brain physiology and function. fMRI techniques are nowadays widely applied in neuroscience research, as well as in translational and clinical studies. The use of animal models in fMRI studies has been fundamental in helping elucidate the mechanisms of cerebral blood-flow regulation, and in the exploration of basic neuroscience questions, such as the mechanisms of perception, behavior, and cognition. Because animals are inherently non-compliant, most fMRI performed to date have required the use of anesthesia, which interferes with brain function and compromises interpretability and applicability of results to our understanding of human brain function. An alternative approach that eliminates the need for anesthesia involves training the animal to tolerate physical restraint during the data acquisition. In the present chapter, we review these two different approaches to obtaining fMRI data from animal models, with a specific focus on the acquisition of longitudinal data from the same subjects.
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Affiliation(s)
- Afonso C Silva
- Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
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Maleki N, Dai W, Alsop DC. Blood flow quantification of the human retina with MRI. NMR IN BIOMEDICINE 2011; 24:104-111. [PMID: 20862658 DOI: 10.1002/nbm.1564] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 04/21/2010] [Indexed: 05/29/2023]
Abstract
The purpose of this study was to investigate the feasibility of measuring blood flow to the retina using arterial spin labeling MRI, a quantitative, noninvasive tomographic technique. Blood flow imaging was performed in a single axial slice through both eyes of five healthy volunteers with no history of retinal diseases. The imaging was optimized to minimize the errors from motion and nonuniform magnetic fields caused by proximity to the sinuses. Key hemodynamic factors for flow quantification, including arterial transit delay and the apparent decay time of the signal, were estimated by repeated measurements with different arterial spin labeling timing. A clearly elevated signal, consistent with the anatomical location of the retina, was observed in all subjects. The measured blood flow to a 1 cm × 1.47 cm section of the retina, centered on the fovea, was 1.75 ± 0.54 µL/mm(2) /min (total blood flow of 261 ± 87 µL/min). The arterial transit delay from a labeling plane 5 cm below the slice was 1137 ± 288 ms. These results establish the feasibility of measuring blood flow to the retina with MRI, and support the future characterization of the healthy and diseased ocular circulation with this method.
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Affiliation(s)
- Nasim Maleki
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Boston, MA, USA.
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Abstract
Modern functional neuroimaging techniques, including functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and optical imaging of intrinsic signals (OIS), rely on a tight coupling between neural activity and cerebral blood flow (CBF) to visualize brain activity using CBF as a surrogate marker. Because CBF is a uniquely defined physiological parameter, fMRI techniques based on CBF contrast have the advantage of being specific to tissue signal change, and the potential to provide more direct and quantitative measures of brain activation than blood oxygenation level-dependent (BOLD)- or cerebral blood volume (CBV)-based techniques. The changes in CBF elicited by increased neural activity are an excellent index of the magnitude of electrical activity. Increases in CBF are more closely localized to the foci of increased electrical activity, and occur more promptly to the stimulus than BOLD- or CBV-based contrast. In addition, CBF-based fMRI is less affected by confounds from venous drainage common to BOLD. Animal studies of brain activation have yielded considerable insights into the advantages of CBF-based fMRI. Based on results provided by animal studies, CBF fMRI may offer a means of better assessing the magnitude, spatial extent, and temporal response of neural activity, and may be more specific to tissue state. These properties are expected to be particularly useful for longitudinal and quantitative fMRI studies.
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Affiliation(s)
- Afonso C Silva
- Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892, USA.
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Abstract
Magnetic resonance evaluation of the pediatric central nervous system is rapidly improving in a number of ways: (1) anatomically with higher resolution; (2) with greater sensitivity to pathological processes characterized by increased water content utilizing fluid attenuated inversion recovery imaging (FLAIR); (3) with greater speed of acquisition with ultrafast (1 s/image) and echo planar imaging techniques (50 ms/image); (4) with measurement of cerebral blood flow as perfusion; (5) with measurement of water proton dispersion (e.g. diffusion imaging); (6) with measurement of biochemical components within tissues with proton spectroscopy; and (7) with evaluation of cortical activation with functional magnetic resonance imaging.
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Affiliation(s)
- R A Zimmerman
- Department of Radiology, The Children's Hospital of Philadelphia, PA 19104, USA
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Schwarzbauer C, Morrissey SP, Haase A. Quantitative magnetic resonance imaging of perfusion using magnetic labeling of water proton spins within the detection slice. Magn Reson Med 1996; 35:540-6. [PMID: 8992204 DOI: 10.1002/mrm.1910350413] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A technique for noninvasive quantitative magnetic resonance imaging of perfusion is presented. It relies on using endogenous water as a freely diffusible tracer. Tissue water proton spins are magnetically labeled by slice-selective inversion, and longitudinal relaxation within the slice is detected using a fast gradient echo magnetic resonance imaging technique. Due to blood flow, nonexcited spins are washed into the slice resulting in an acceleration of the longitudinal relaxation process. Incorporating this phenomenon into the Bloch equation yields an expression that allows quantification of perfusion on the basis of a slice-selective and a nonselective inversion recovery experiment. Based on this technique, quantitative parameter maps of the regional cerebral blood flow (rCBF) were obtained from eight rats. Evaluation of regions of interest within the cerebral hemispheres yielded an average rCBF value of 104 +/- 21 ml/min/100 g, which increased to 219 +/- 30 ml/min/100 g during hypercapnia. The measured rCBF values are in good agreement with previously reported literature values.
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Affiliation(s)
- C Schwarzbauer
- Institut für Luft- und Raumfahrtmedizin, DLR, Köln, Germany
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Venkatasubramanian PN, Shen YJ, Wyrwicz AM. In vivo 19F-NMR spectroscopic study of halothane uptake in rabbit brain. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1245:262-8. [PMID: 7492587 DOI: 10.1016/0304-4165(95)00086-q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Uptake of a fluorinated anesthetic, halothane, in rabbit brain and blood was studied using 19F-NMR spectroscopic techniques. Localized one-dimensional chemical shift imaging and non-localized one-pulse sequence were used to measure brain uptake kinetics in vivo. Halothane signal was found predominantly in the cerebral cortex. Uptake in the brain followed a first-order biexponential kinetics. The average half-lives were 4 min and 70 min, respectively, for the 'fast' and 'slow' phases of the uptake. Uptake in the arterial blood was also biexponential. However, equilibration of halothane in the brain considerably lagged behind that in arterial blood. This delay was ascribed to a 'restricted diffusion' of the anesthetic molecule into brain tissue.
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Koretsky AP, Costa e Silva A, Williams DS, Zhang W, Detre JA. Magnetic Resonance Imaging of Cerebral Blood Flow**The Pittsburgh NMR Center for Biomedical Research was established by grants from the Richard King Mellon Foundation, the Lucille P. Markey Charitable Trust, the Ben Franklin Partnership Program of the Commonwealth of Pennsylvania, and the Ralph M. Parsons Foundation. The work described was supported by a National Institutes of Health, Division of Research Resources Award RR-03631 to the Pittsburgh NMR Center for Biomedical Research, NIH Research Career Development Award (HL-02847) to APK, NIH Clinical Investigator Development Award (NS-01668) to JAD, and a Brazilian CNPq fellowship to ACS. Cerebrovasc Dis 1995. [DOI: 10.1016/b978-0-7506-9603-6.50046-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Pekar J, Ligeti L, Sinnwell T, Moonen CT, Frank JA, McLaughlin AC. 19F magnetic resonance imaging of cerebral blood flow with 0.4-cc resolution. J Cereb Blood Flow Metab 1994; 14:656-63. [PMID: 8014213 DOI: 10.1038/jcbfm.1994.82] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
19F magnetic resonance imaging techniques were used to determine "wash-in" and "wash-out" curves of the inert, diffusible gas CHF3 from 0.4-cc voxels in the cat brain, and mass spectrometer gas detection was used to determine the CHF3 concentration in expired air. These two sets of data were used to calculate cerebral blood flow values in the 0.4-cc voxels, and the blood flow images were registered with high-resolution 1H magnetic resonance images. Data were collected both during the wash-in and wash-out phases of the experiment, but the two sets of data were analyzed separately to obtain independent estimates of the blood flow during the two phases, i.e., Qin and Qout. Repeated determinations of cerebral blood flow images were performed in individual animals, and the entire protocol was repeated on five different animals. The average values of Qin and Qout for a typical 0.4-cc voxel in the parietal cortex were 83 ml 100 g-1 min-1 and 72 ml 100 g-1 min-1, respectively. Monte Carlo calculations utilizing the noise in the 19F NMR signal from this voxel predict an average standard deviation for Qin and Qout of +/- 10%. The average standard deviation for repeated measurements (in the same animal) of Qin and Qout in this voxel was +/- 14%. We conclude that 19F magnetic resonance imaging approaches have the potential to image cerebral blood flow in humans.
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Affiliation(s)
- J Pekar
- Laboratory for Diagnostic Radiology Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892
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Roberts DA, Detre JA, Bolinger L, Insko EK, Leigh JS. Quantitative magnetic resonance imaging of human brain perfusion at 1.5 T using steady-state inversion of arterial water. Proc Natl Acad Sci U S A 1994; 91:33-7. [PMID: 8278387 PMCID: PMC42880 DOI: 10.1073/pnas.91.1.33] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We report our experience using a noninvasive magnetic resonance technique for quantitative imaging of human brain perfusion at 1.5 T. This technique uses magnetically inverted arterial water as a freely diffusible blood flow tracer. A perfusion image is calculated from magnetic resonance images acquired with and without arterial blood inversion and from an image of the apparent spin-lattice relaxation time. Single-slice perfusion maps were obtained from nine volunteers with approximately 1 x 2 x 5-mm resolution in an acquisition time of 15 min. Analysis yielded average perfusion rates of 93 +/- 16 ml.100 g-1.min-1 for gray matter, 38 +/- 10 ml.100 g-1.min-1 for white matter, and 52 +/- 8 ml.100 g-1.min-1 for whole brain. Significant changes in perfusion were observed during hyperventilation and breath holding. This technique may be used for quantitative measurement of perfusion in human brain without the risks and expense of methods which use exogenous tracers.
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Affiliation(s)
- D A Roberts
- Department of Radiology, University of Pennsylvania, Philadelphia 19104
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Walsh TR, Detre JA, Koretsky AP, Simplaceanu E, Halow JM, Rao P, Makowka L, Ho C. Response of normal and reperfused livers to glucagon stimulation: NMR detection of blood flow and high-energy phosphates. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1181:7-14. [PMID: 8457608 DOI: 10.1016/0925-4439(93)90083-d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effects of glucagon on blood flow and high-energy phosphates in control and in rat livers damaged by ischemia were studied using in vivo nuclear magnetic resonance (NMR) spectroscopy. Normal livers and livers which had been made ischemic for 20, 40, and 60 min followed by 60 min of reperfusion were studied. Ischemia led to a loss in adenosine triphosphate (ATP) within 30 min. Reperfusion after 20 min of ischemia led to complete recovery of ATP. 60 min of reperfusion after 40 or 60 min of ischemia led to only a 76% and 48% recovery of ATP, respectively. Glucagon, at doses up to 2.5 mg/kg body weight, caused no changes in the inorganic phosphate (P(i)) to ATP ratio in normal livers as measured by 31P-NMR spectroscopy. In livers which had been made ischemic for 20, 40, or 60 min, glucagon caused an increase in the P(i)/ATP ratio of 18%, 40%, and 40%, respectively. 19F-NMR detection of the washout of trifluoromethane from liver was used to measure blood flow. Glucagon-stimulated flow in the normal liver in a dose-dependent manner, with 2.5 mg glucagon/kg body weight leading to a 95% increase in flow. Ischemia for 20, 40, and 60 min followed by 60 min of reperfusion led to hepatic blood flows which were 63%, 68%, and 58% lower than control liver. In reperfused livers, blood flow after glucagon-stimulation was reduced to 56%, 43%, and 48% of control glucagon-stimulated flow after 20, 40, and 60 min of ischemia. These results indicate that ischemia followed by reperfusion leads to decreases in hepatic blood flow prior to alterations in ATP and the response of the liver to glucagon is altered in the reperfused liver.
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Affiliation(s)
- T R Walsh
- Pittsburgh NMR Center for Biomedical Research, PA
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Branch CA, Ewing JR, Helpern JA, Ordidge RJ, Butt S, Welch KM. Atraumatic quantitation of cerebral perfusion in cats by 19F magnetic resonance imaging. Magn Reson Med 1992; 28:39-53. [PMID: 1435220 DOI: 10.1002/mrm.1910280105] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have noninvasively produced low-resolution, quantitative nuclear magnetic resonance images of cerebral blood flow in 2-ml voxels in eight cats. Typical signal-to-noise of 4 to 1 was obtained in cerebral voxels in 16.5-s epochs. Mean flow during normocapnia (paCO2 = 39 +/- 4 mm Hg) and hypercapnia (paCO2 = 62 +/- 4 mm Hg) was 53 +/- 20 ml/100 g-min and 140 +/- 36 ml/100 g-min, respectively. Fast flows in normocapnia were 94 +/- 13 and 182 +/- 39 ml/100 g-min in hypercapnia. These results suggest that an atraumatic quantitative imaging assessment of cerebral perfusion may be possible in humans using these techniques.
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Affiliation(s)
- C A Branch
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan 48202
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Zhang W, Williams DS, Detre JA, Koretsky AP. Measurement of brain perfusion by volume-localized NMR spectroscopy using inversion of arterial water spins: accounting for transit time and cross-relaxation. Magn Reson Med 1992; 25:362-71. [PMID: 1614321 DOI: 10.1002/mrm.1910250216] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The theoretical model for perfusion measurement by NMR using arterial labeling of endogenous water is extended to include the effects of transit time and cross-relaxation of tissue water with macromolecules. Water magnetization in rat brain is monitored using the STEAM method to simultaneously determine the transit time, magnetization transfer rate constant, and perfusion. The results show that the transit time in rat brain is quite short, and thus its effect on perfusion measurement is small. It is also demonstrated both theoretically and experimentally that the steady-state effects of cross-relaxation with macromolecules on perfusion measurement are accounted for by a proper control experiment.
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Affiliation(s)
- W Zhang
- Pittsburgh NMR Center for Biomedical Research, Pennsylvania
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17
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Abstract
Measurement of tissue perfusion is important for the functional assessment of organs in vivo. Here we report the use of 1H NMR imaging to generate perfusion maps in the rat brain at 4.7 T. Blood water flowing to the brain is saturated in the neck region with a slice-selective saturation imaging sequence, creating an endogenous tracer in the form of proximally saturated spins. Because proton T1 times are relatively long, particularly at high field strengths, saturated spins exchange with bulk water in the brain and a steady state is created where the regional concentration of saturated spins is determined by the regional blood flow and regional T1. Distal saturation applied equidistantly outside the brain serves as a control for effects of the saturation pulses. Average cerebral blood flow in normocapnic rat brain under halothane anesthesia was determined to be 105 +/- 16 cc.100 g-1.min-1 (mean +/- SEM, n = 3), in good agreement with values reported in the literature, and was sensitive to increases in arterial pCO2. This technique allows regional perfusion maps to be measured noninvasively, with the resolution of 1H MRI, and should be readily applicable to human studies.
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Affiliation(s)
- J A Detre
- Metabolic Magnetic Resonance Research Center, University of Pennsylvania School of Medicine, Philadelphia 19104
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Williams DS, Detre JA, Leigh JS, Koretsky AP. Magnetic resonance imaging of perfusion using spin inversion of arterial water. Proc Natl Acad Sci U S A 1992; 89:212-6. [PMID: 1729691 PMCID: PMC48206 DOI: 10.1073/pnas.89.1.212] [Citation(s) in RCA: 1127] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A technique has been developed for proton magnetic resonance imaging (MRI) of perfusion, using water as a freely diffusable tracer, and its application to the measurement of cerebral blood flow (CBF) in the rat is demonstrated. The method involves labeling the inflowing water proton spins in the arterial blood by inverting them continuously at the neck region and observing the effects of inversion on the intensity of brain MRI. Solution to the Bloch equations, modified to include the effects of flow, allows regional perfusion rates to be measured from an image with spin inversion, a control image, and a T1 image. Continuous spin inversion labeling the arterial blood water was accomplished, using principles of adiabatic fast passage by applying continuous-wave radiofrequency power in the presence of a magnetic field gradient in the direction of arterial flow. In the detection slice used to measure perfusion, whole brain CBF averaged 1.39 +/- 0.19 ml.g-1.min-1 (mean +/- SEM, n = 5). The technique's sensitivity to changes in CBF was measured by using graded hypercarbia, a condition that is known to increase brain perfusion. CBF vs. pCO2 data yield a best-fit straight line described by CBF (ml.g-1.min-1) = 0.052pCO2 (mm Hg) - 0.173, in excellent agreement with values in the literature. Finally, perfusion images of a freeze-injured rat brain have been obtained, demonstrating the technique's ability to detect regional abnormalities in perfusion.
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Affiliation(s)
- D S Williams
- Pittsburgh Nuclear Magnetic Resonance Center for Biomedical Research, Carnegie Mellon University, PA 15213
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19
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Neil JJ. The use of freely diffusible, NMR-detectable tracers for measuring organ perfusion. ACTA ACUST UNITED AC 1991. [DOI: 10.1002/cmr.1820030102] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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van Zijl PC, Ligeti L, Sinnwell T, Alger JR, Chesnick AS, Moonen CT, McLaughlin AC. Measurement of cerebral blood flow by volume-selective 19F NMR spectroscopy. Magn Reson Med 1990; 16:489-95. [PMID: 2077340 DOI: 10.1002/mrm.1910160316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A stimulated echo sequence was used to obtain 19F NMR spectra from within a 4-ml voxel in a cat brain. The time dependence of the 19F NMR signal from an inert gas (CHF3) was used to calculate the blood flow in the voxel. The position of the voxel was selected using a 1H MR image.
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Affiliation(s)
- P C van Zijl
- Medicine Branch, NCI, National Institutes of Health, Bethesda, Maryland 20892
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